multidim-array-index

> maps multidimensional array indices to monodimensional array index


Table Of Contents:

* Installation
* Examples
- 1th-order
- 2th-order
- 3th-order
* API
* License

Installation

With npm do

``bash
npm install multidim-array-index
`

Examples

All code in the examples below is intended to be contained into a single file.

`
var multiDimArrayIndex = require('multidim-array-index')
`

$3

In the monodimensional case, it just returns the index itself.

`javascript
var i3 = multiDimArrayIndex.bind(null, [3])

i3([0]) // 0
i3([1]) // 1
i3([2]) // 2
`

$3

For a two dimensional case, for instance a matrix, it is equivalent to the
function (i, j, numCols) => j + i * numCols

`javascript
var i2x3 = multiDimArrayIndex.bind(null, [2, 3])

i2x3([0, 0]) // 0
i2x3([0, 1]) // 1
i2x3([0, 2]) // 2
i2x3([1, 0]) // 3
i2x3([1, 1]) // 4
i2x3([1, 2]) // 5
`

$3

`javascript
var i2x3x4 = multiDimArrayIndex.bind(null, [2, 2, 2])

i2x3x4([0, 0, 0]) // 0
i2x3x4([0, 0, 1]) // 1
i2x3x4([0, 0, 2]) // 2
i2x3x4([0, 0, 3]) // 3
i2x3x4([0, 1, 0]) // 4
i2x3x4([0, 1, 1]) // 5
i2x3x4([0, 1, 2]) // 6
i2x3x4([0, 1, 3]) // 7
i2x3x4([1, 0, 0]) // 8
i2x3x4([1, 0, 1]) // 9
i2x3x4([1, 0, 2]) // 10
i2x3x4([1, 0, 3]) // 11
i2x3x4([1, 1, 0]) // 12
i2x3x4([1, 1, 1]) // 13
i2x3x4([1, 1, 2]) // 14
i2x3x4([1, 1, 3]) // 15

i2x2x2([0, 0, 0]) //// 0
i2x2x2([0, 0, 1]) // 1
i2x2x2([0, 1, 0]) // 2
i2x2x2([0, 1, 1]) // 3
i2x2x2([1, 0, 0]) // 4
i2x2x2([1, 0, 1]) // 5
i2x2x2([1, 1, 0]) // 6
i2x2x2([1, 1, 1]) // 7
`

API

$3

* @param {Array} dimensions defines the shape of the multi dimensional array
* @param {Array} indices to transform
* @returns {Number} index of an equivalent mono dimensional array

Given dimensions d_1, d_2, d_3 .. d_n and indices i_1, i_2, i_3 .. i_n index
is computed by formula

`
index = i_n + i_(n-1) d_n + i_(n-2) d_n d_(n-1) + ... + i_2 d_n d_(n-1) ... d_3 + i_1 d_n ... d_2
`

$3

An object exposing the following error messages:

* outOfBoundIndex

For example, the following snippets will throw

`javascript
// outOfBoundIndex

i3([11])
i2x3x4([2, 3, 5])
``

License

MIT